cleanup

Author: siddacious

adafruit_scd30.py

@@ -80,12 +80,14 @@ def reset(self):
 
     @property
     def measurement_interval(self):
-        """Sets the interval between readings"""
-        # raise RuntimeError("NOT WORKING")
+        """Sets the interval between readings in seconds. The interval value must be from 2-1800"""
+
         return self._read_register(_CMD_SET_MEASUREMENT_INTERVAL)
 
     @measurement_interval.setter
     def measurement_interval(self, value):
+        if value < 2 or value > 1800:
+            raise AttributeError("measurement_interval must be from 2-1800 seconds")
         self._send_command(_CMD_SET_MEASUREMENT_INTERVAL, value)
 
     @property
@@ -102,30 +104,9 @@ def self_calibration_enabled(self):
     def self_calibration_enabled(self, enabled):
         self._send_command(_CMD_AUTOMATIC_SELF_CALIBRATION, enabled)
 
-    def _send_command(self, command, arguments=None):
-        if arguments is not None:
-            self._crc_buffer[0] = arguments >> 8
-            self._crc_buffer[1] = arguments & 0xFF
-            self._buffer[2] = arguments >> 8
-            self._buffer[3] = arguments & 0xFF
-            crc = self._crc8(self._crc_buffer)
-            self._buffer[4] = crc
-            end_byte = 5
-        else:
-            end_byte = 2
-
-        self._buffer[0] = command >> 8
-        self._buffer[1] = command & 0xFF
-
-        with self.i2c_device as i2c:
-            i2c.write(self._buffer, end=end_byte)
-
     @property
-    def _data_available(self):
-        """
-    Check the sensor to see if new data is available
-    """
-
+    def data_available(self):
+        """Check the sensor to see if new data is available"""
         return self._read_register(_CMD_GET_DATA_READY)
 
     @property
@@ -155,13 +136,17 @@ def altitude(self, altitude):
     @property
     def temperature_offset(self):
         """Specifies the offset to be added to the reported measurements to account for a bias in
-        the measured signal."""
+        the measured signal. Value is  in degrees C with a resolution of 0.01 degrees and a maximum
+        value of 655.35"""
         raw_offset = self._read_register(_CMD_SET_TEMPERATURE_OFFSET)
         return raw_offset / 100.0
 
     @temperature_offset.setter
     def temperature_offset(self, offset):
-        # TODO: check value before set
+        if offset > 655.35:
+            raise AttributeError(
+                "Offset value must be less than or equal to 655.35 degrees C"
+            )
 
         self._send_command(_CMD_SET_TEMPERATURE_OFFSET, int(offset * 100))
 
@@ -178,20 +163,59 @@ def forced_recalibration_reference(self):
     def forced_recalibration_reference(self, reference_value):
         self._send_command(_CMD_SET_FORCED_RECALIBRATION_FACTOR, reference_value)
 
+    @property
+    def co2(self):
+        """Returns the CO2 concentration in PPM (parts per million)
+
+        Between measurements, the most recent reading will be cached and returned."""
+        if self.data_available:
+            self._read_data()
+        return self._co2
+
+    @property
+    def temperature(self):
+        """Returns the current temperature in degrees celcius
+
+        Between measurements, the most recent reading will be cached and returned."""
+        if self.data_available:
+            self._read_data()
+        return self._temperature
+
+    @property
+    def relative_humidity(self):
+        """Returns the current relative humidity in %rH.
+
+        Between measurements, the most recent reading will be cached and returned. """
+        if self.data_available:
+            self._read_data()
+        return self._relative_humitidy
+
+    def _send_command(self, command, arguments=None):
+        # if there is an argument, calculate the CRC and include it as well.
+        if arguments is not None:
+            self._crc_buffer[0] = arguments >> 8
+            self._crc_buffer[1] = arguments & 0xFF
+            self._buffer[2] = arguments >> 8
+            self._buffer[3] = arguments & 0xFF
+            crc = self._crc8(self._crc_buffer)
+            self._buffer[4] = crc
+            end_byte = 5
+        else:
+            end_byte = 2
+
+        self._buffer[0] = command >> 8
+        self._buffer[1] = command & 0xFF
+
+        with self.i2c_device as i2c:
+            i2c.write(self._buffer, end=end_byte)
+
     def _read_register(self, reg_addr):
         self._buffer[0] = reg_addr >> 8
         self._buffer[1] = reg_addr & 0xFF
         with self.i2c_device as i2c:
             i2c.write_then_readinto(self._buffer, self._buffer, out_end=2, in_end=2)
         return unpack_from(">H", self._buffer)[0]
 
-    @property
-    def co2(self):
-        """Returns the CO2 concentration in PPM (parts per million)"""
-        if self._data_available:
-            self._read_data()
-        return self._co2
-
     def _read_data(self):
         self._send_command(_CMD_READ_MEASUREMENT)
         with self.i2c_device as i2c:

examples/scd30_simpletest.py

@@ -1,7 +1,6 @@
 # SPDX-FileCopyrightText: 2020 by Bryan Siepert, written for Adafruit Industries
 #
 # SPDX-License-Identifier: Unlicense
-# pylint:disable=protected-access
 import time
 import board
 import busio
@@ -11,12 +10,13 @@
 scd = adafruit_scd30.SCD30(i2c)
 
 while True:
-    data = scd._data_available
-    if data:
+    # since the measurement interval is long (2+ seconds) we check for new data before reading
+    # the values, to ensure current readings.
+    if scd.data_available:
         print("Data Available!")
         print("CO2:", scd.co2, "PPM")
-        print("Temperature:", scd._temperature, "degrees C")
-        print("Humidity::", scd._relative_humitidy, "%%rH")
+        print("Temperature:", scd.temperature, "degrees C")
+        print("Humidity:", scd.relative_humidity, "%%rH")
         print("")
         print("Waiting for new data...")
         print("")

examples/scd30_tuning_knobs.py

@@ -1,15 +1,14 @@
 # SPDX-FileCopyrightText: 2020 by Bryan Siepert, written for Adafruit Industries
 #
 # SPDX-License-Identifier: Unlicense
-# pylint:disable=protected-access
 import time
 import board
 import busio
 import adafruit_scd30
 
 i2c = busio.I2C(board.SCL, board.SDA)
 scd = adafruit_scd30.SCD30(i2c)
-# scd.temperature_offset = 5.5
+# scd.temperature_offset = 10
 print("Temperature offset:", scd.temperature_offset)
 
 # scd.measurement_interval = 4
@@ -21,19 +20,20 @@
 # scd.ambient_pressure = 1100
 print("Ambient Pressure:", scd.ambient_pressure)
 
-# scd.altitude = 1600
+# scd.altitude = 100
 print("Altitude:", scd.altitude, "meters above sea level")
 
 # scd.forced_recalibration_reference = 409
 print("Forced recalibration reference:", scd.forced_recalibration_reference)
 print("")
+
 while True:
-    data = scd._data_available
+    data = scd.data_available
     if data:
         print("Data Available!")
         print("CO2:", scd.co2, "PPM")
-        print("Temperature:", scd._temperature, "degrees C")
-        print("Humidity::", scd._relative_humitidy, "%%rH")
+        print("Temperature:", scd.temperature, "degrees C")
+        print("Humidity::", scd.relative_humidity, "%%rH")
         print("")
         print("Waiting for new data...")
         print("")